From: Nanyong Sun Date: Thu, 5 Sep 2024 15:31:18 +0000 (+0800) Subject: mm: migrate: simplify find_mm_struct() X-Git-Tag: v6.12-rc1~115^2~51 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=46dcc7c92e63879a49cfbd99949858df0335a122;p=thirdparty%2Flinux.git mm: migrate: simplify find_mm_struct() Use find_get_task_by_vpid() to replace the task_struct find logic in find_mm_struct(), note that this patch move the ptrace_may_access() call out from rcu_read_lock() scope, this is ok because it actually does not need it, find_get_task_by_vpid() already get the pid and task safely, ptrace_may_access() can use the task safely, like what sched_core_share_pid() similarly do. Link: https://lkml.kernel.org/r/20240905153118.1205173-1-sunnanyong@huawei.com Signed-off-by: Nanyong Sun Cc: Kefeng Wang Signed-off-by: Andrew Morton --- diff --git a/mm/migrate.c b/mm/migrate.c index 35cc9d35064b0..6a68d9923820b 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -2505,25 +2505,19 @@ static struct mm_struct *find_mm_struct(pid_t pid, nodemask_t *mem_nodes) return current->mm; } - /* Find the mm_struct */ - rcu_read_lock(); - task = find_task_by_vpid(pid); + task = find_get_task_by_vpid(pid); if (!task) { - rcu_read_unlock(); return ERR_PTR(-ESRCH); } - get_task_struct(task); /* * Check if this process has the right to modify the specified * process. Use the regular "ptrace_may_access()" checks. */ if (!ptrace_may_access(task, PTRACE_MODE_READ_REALCREDS)) { - rcu_read_unlock(); mm = ERR_PTR(-EPERM); goto out; } - rcu_read_unlock(); mm = ERR_PTR(security_task_movememory(task)); if (IS_ERR(mm))